U.S. patent application number 12/568146 was filed with the patent office on 2010-03-04 for optical transmission module, connecting part, and electronic device having optical transmission module.
This patent application is currently assigned to OMRON CORPORATION. Invention is credited to Akira Enami, Hayami Hosokawa, Yoshihisa Ishida, Toshiaki Okuno, Hiroshi Sameshima, Akihiko Sano, Junichi Tanaka, Naru Yasuda.
Application Number | 20100054672 12/568146 |
Document ID | / |
Family ID | 38609574 |
Filed Date | 2010-03-04 |
United States Patent
Application |
20100054672 |
Kind Code |
A1 |
Tanaka; Junichi ; et
al. |
March 4, 2010 |
OPTICAL TRANSMISSION MODULE, CONNECTING PART, AND ELECTRONIC DEVICE
HAVING OPTICAL TRANSMISSION MODULE
Abstract
A connection member (21), which electrically connects a package
(14) on which an optical element that converts an electric signal
to an optical signal or converts an optical signal to an electric
signal and at least one end portion including an incident/releasing
port for an optical signal of an optical waveguide (11) that is
optically coupled with the optical element to transmit the optical
signal are mounted, and a second substrate (2) to each other, is
provided with a holding unit having elasticity, which holds the
package (14), and a connection unit that is connected to the
substrate (2).
Inventors: |
Tanaka; Junichi; (Nara-shi,
JP) ; Sano; Akihiko; (Uji-shi, JP) ; Okuno;
Toshiaki; (Nara-shi, JP) ; Ishida; Yoshihisa;
(Otsu-shi, JP) ; Enami; Akira; (Nara-shi, JP)
; Sameshima; Hiroshi; (Nara-shi, JP) ; Yasuda;
Naru; (Uji-shi, JP) ; Hosokawa; Hayami;
(Tsuzuki-gun, JP) |
Correspondence
Address: |
OSHA LIANG L.L.P.
TWO HOUSTON CENTER, 909 FANNIN, SUITE 3500
HOUSTON
TX
77010
US
|
Assignee: |
OMRON CORPORATION
Kyoto-shi
JP
|
Family ID: |
38609574 |
Appl. No.: |
12/568146 |
Filed: |
September 28, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12296516 |
Oct 8, 2008 |
|
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PCT/JP2007/058145 |
Apr 13, 2007 |
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12568146 |
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Current U.S.
Class: |
385/88 |
Current CPC
Class: |
G02B 6/4214 20130101;
G02B 6/43 20130101; G02B 6/4201 20130101 |
Class at
Publication: |
385/88 |
International
Class: |
G02B 6/36 20060101
G02B006/36 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 14, 2006 |
JP |
2006-112774 |
Claims
1. A connection member, which electrically connects an optical
element configured to convert an electric signal to an optical
signal or to convert an optical signal to an electric signal, a
first substrate including an incident/releasing port of an optical
transmission path for an optical signal at least one end portion
thereof, and a second substrate to each other, wherein the optical
transmission path is optically coupled with the optical element to
transmit the optical the connection, the connection member
comprising: a holding unit having elasticity, which holds the first
substrate; and a connection unit connected to the second substrate,
wherein the holding unit is provided with an electrode at a
connecting position to the first substrate, and holds the first
substrate by connecting the first substrate to the electrode.
2. The connection member according to claim 1, wherein the holding
unit is installed on the second substrate.
3. The connection member according to claim 1, wherein the holding
unit holds a face of the first substrate that intersects with a
face opposing to the second substrate face that is connected to the
connection unit.
4. The connection member according to claim 3, further comprising:
at least one pair of the holding units, wherein the paired holding
units apply pressing forces in opposing directions to the first
substrate so as to hold the first substrate.
5. The connection member according to claim 3, wherein the
connection unit is formed into a concave shape to receive the first
substrate, and the holding unit is formed on a face that faces an
inner space in the concave portion.
6. (canceled)
7. The connection member according to claim 1, wherein the
connection unit is provided with an electrode pin that is
electrically connected to the second substrate.
8-20. (canceled)
21. The connection member according to claim 2, wherein the holding
unit holds a face of the first substrate that intersects with a
face opposing to the second substrate face that is connected to the
connection unit.
22. The connection member according to claim 4, wherein the
connection unit is formed into a concave shape to receive the first
substrate, and the holding unit is formed on a face that faces an
inner space in the concave portion.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application and claims
benefit under 35 U.S.C. .sctn.120 of U.S. patent application Ser.
No. 12/296,516, filed on Oct. 8, 2008, entitled "Optical
Transmission Module, Connection Part, and Electronic Device having
Optical Transmission Module," in the name of Junichi Tanaka et
al.
TECHNICAL FIELD
[0002] The present invention relates to an optical communication
cable module, and more particularly concerns a connection structure
of an optical transmission module to a substrate.
BACKGROUND ART
[0003] In recent years, there have been strong demands for a data
transmission module capable of high-speed data communication with a
large capacity, which is superior in space property and noise
resistant property, and can be mounted on small-size, thin consumer
appliances. Examples of the data communication in consumer
appliances include data communication between a display and a
mother board in a notebook computer and data communication between
a display and a mother board in a PDA (Personal Digital Assistant).
In recent years, in an attempt to achieve high-speed data
communication with a large capacity in these small-size, thin
consumer appliances, since data communication by the use of
electric signals has limitations in the communication speed and the
module space, data communication by the use of optical signals has
been utilized. In the data communication by the use of optical
signals, an optical transmission module that converts an electric
signal to an optical signal, and transmits the optical signal has
been used. With this arrangement, optical transmission among
substrates in the apparatus can be executed.
[0004] The following description will briefly discuss the system of
data communication utilizing the optical communication module.
Here, in order to execute data communication inside an apparatus,
the optical transmission module is supposed to have a structure in
which one end of the optical transmission module is mounted on a
substrate A, with the other end of the optical transmission module
being mounted on a substrate B. Moreover, the following explanation
will be given by exemplifying a transmission path for transmitting
an optical signal as an optical waveguide.
[0005] First, an electric signal, transmitted through the substrate
A, is inputted to a photoelectric conversion element
(light-receiving/emitting element, optical element) a on the
transmission side where it is converted to an optical signal. The
photoelectric conversion element a transmits the optical signal
thus converted toward an optical waveguide (optical transmission
path). The optical signal, transmitted from the photoelectric
conversion element a, is made incident on an incident port of an
optical signal in the optical waveguide, and propagated through the
waveguide. Then, the optical signal is released from a releasing
port of an optical signal in the optical waveguide, and received by
a photoelectric conversion element (light-receiving/emitting
element, optical element) b on the light-receiving side. The
optical signal, received by the photoelectric conversion element b,
is converted to an electric signal, and the resulting electric
signal is transmitted through the substrate B.
[0006] By electrically connecting the optical transmission module
to the substrate in this manner, data communication is executed in
the apparatus.
[0007] Here, conventionally, various methods for connecting an
optical transmission module to a substrate have been proposed. For
example, an optical transmission module described in Patent
Document 1 is provided with electrode pins, and designed so that
the electrode pins are secured to the substrate by soldering. FIG.
34 is a side view that shows a schematic structure of an optical
transmission module 100 described in Patent Document 1. As shown in
this Figure, a package 104 on which a sub-substrate 103 having an
optical waveguide 101 and a light-receiving/emitting element 102
assembled therein has been mounted is provided with an electrode
pin 105 that allows electrical connection to the substrate 106.
Thus, since the optical communication module 100 is secured onto
the substrate 106 through the electrode pin 105, data communication
is available between apparatuses (not shown) by utilizing optical
transmission.
[0008] Moreover, Patent Document 2 has described a structure in
which an optical transmission module is connected to a substrate by
using an electric connector. FIG. 35 is a side view that shows a
schematic structure of an optical transmission module 200 described
in Patent Document 2. As shown in this Figure, a sub-substrate 203
on which an optical waveguide 201 and a light-receiving/emitting
element 202 have been mounted is provided with an electric
connector 204 that allows electrical connection to a substrate 205.
With this arrangement, since the optical transmission module 200
can be secured to the substrate 205 through the electric connector
204, data communication is available between apparatuses (not
shown) by utilizing optical transmission, in the same manner as in
Patent Document 1. [0009] Patent Document 1: Japanese Patent
Application Laid-Open "JP-A No. 2005-321560 (published on Nov. 17,
2005)" [0010] Patent Document 2: Japanese Patent Application
Laid-Open "JP-A No. 2006-42307 (published on Feb. 9, 2006)"
[0011] Here, in order to transmit an optical signal by using an
optical waveguide, the incident/releasing port of an optical signal
in the optical waveguide and the light-receiving/emitting element
need to be properly positioned and optically coupled with each
other. As described above, the light-receiving/emitting element is
an element that converts an electric signal transmitted thereto
from an external device through the substrate to an optical signal
and transmits the optical signal, and also receives an optical
signal and converts it to an electric signal. Here, in order to
achieve stable data transmission, it is necessary to maintain
constant the distance between the incident/releasing port of an
optical signal in the light-receiving/emitting element and the
incident/releasing port of an optical signal in the optical
waveguide, as well as the positional relationship between the two
ports.
[0012] However, the above-mentioned conventional structure has the
following problems.
[0013] That is, in the structure described in Patent Document 1,
the optical transmission module 100 and the substrate 106 are
firmly secured to each other by soldering; therefore, for example,
in a case where, upon securing the two members by soldering, a warp
or the like occurs in the sub-substrate 103 or the package 104 of
the optical transmission module 100, the optical transmission
module 100 is secured in a deformed state, as it is. Moreover, even
in a case where the optical transmission module 100 and the
substrate 106 are connected to each other without any problems,
since the optical transmission module 100 and the substrate 106 are
brought into a firmly secured state by soldering, a deformation
occurring in the substrate 106 due to an external force or the like
applied thereto might be transferred to the optical transmission
module 100. Moreover, since the above-mentioned structure uses
solder, the optical waveguide might be deformed or damaged by
influences of reflow heat.
[0014] In this manner, in a case where a deformation occurs in the
sub-substrate 103 on which the optical waveguide 101 and the
light-receiving/emitting element 102 are mounted, the package 104
or the optical waveguide 101 itself, since the distance between the
incident/releasing port of an optical signal in the
light-receiving/emitting element 102 and the incident/releasing
port of an optical signal in the optical waveguide 101, as well as
the positional relationship between the two ports, is changed, the
optical coupling efficiency is varied to cause a problem of failure
in transmitting data stably.
[0015] In particular, in a case of an optical waveguide having high
flexibility, since a polymer waveguide is used in most cases, the
waveguide is more susceptible to influences by heat. For this
reason, it becomes very difficult to carry out data transmission in
a stable manner.
[0016] Moreover, in the structure described in Patent Document 2,
since an optical transmission module 200 is connected to a
substrate 205 through an electric connector 204, a space used for
mounting the electric connector 204 is required to cause a problem
in that the entire module becomes bulky. Moreover, in a case of the
connection using the electric connector 204, when the substrate 205
receives a stress in a rotation direction .theta. around an
insertion direction (Z-axis) of the connector, the connection unit
of the electric connector 204 in the optical transmission module
200 also receives the same stress, and the connection unit
consequently tends to be damaged. As a result, coming off of the
electric connector 204 or the like tends to occur, failing to carry
out normal electrical communication to cause adverse effects in the
optical transmission.
[0017] Here, specific examples of the method for connecting an
optical transmission path include a method using a ferrule as a
holding member and a directly pasting method onto an optical
element. However, the method using the ferrule requires a space for
connectors, with the result that the entire module becomes bulky.
Moreover, when applied to a small-size apparatus, this structure is
more susceptible to influences from vibration and impact, and
deviations in the optical axis tend to occur, failing to carry out
data transmission in a stable manner. In contrast, the method for
directly pasting an optical transmission path onto an optical
element causes a deformation of the substrate to be transferred to
the optical transmission path, with the result that deviations in
the optical axis tend to occur, failing to carry out data
transmission in a stable manner.
[0018] In view of the above-mentioned various problems, the present
invention has been devised, and its objective is to provide an
optical transmission module having a small size that is capable of
carrying out stable data transmission, a connection member and an
electronic apparatus equipped with such an optical transmission
module.
DISCLOSURE OF THE INVENTION
[0019] In order to solve the above-mentioned problems, a connection
member in accordance with the present invention, which electrically
connects a first substrate on which an optical element that
converts an electric signal to an optical signal or converts an
optical signal to an electric signal and at least one end portion
including an incident/releasing port for an optical signal of an
optical transmission path that is optically coupled with the
optical element to transmit the optical signal are mounted, and a
second substrate to each other, is characterized by including a
holding unit having elasticity, which holds the first substrate,
and a connection unit that is connected to the second
substrate.
[0020] Here, the optical transmission path is a cable used for
transmitting an optical signal, and specific examples thereof
include an optical waveguide and an optical fiber.
[0021] Moreover, the material used for the holding unit includes
any elastic material as long as it can absorb vibration, impact or
the like, and specific examples thereof include rubber, springs,
adhesive sheets and resin.
[0022] In accordance with the above-mentioned structure, the first
substrate is connected to the second substrate through the
connection member.
[0023] With this arrangement, since the first substrate is held by
the holding unit having elasticity, it is allowed to move relative
to the second substrate. For this reason, even in a case where a
deformation such as a warp occurs in the second substrate due to
influences from, for example, an external force or heat, since the
amount of deformation is absorbed by the holding unit, no
deformation occurs in the first substrate.
[0024] In order to achieve stable data transmission, it is
necessary to maintain constant the distance between the
incident/releasing portion for an optical signal of the optical
element and the incident/releasing port for an optical signal of
the optical waveguide, that is, the positional relationship between
the optical element and the optical waveguide.
[0025] Conventionally, the second substrate and the first substrate
have an integrally fixed structure by using solder or the like;
consequently, when a deformation occurs in the second substrate,
the subsequent deformation also occurs in the first substrate. For
this reason, the positional relationship between the optical
element mounted on the first substrate and the optical waveguide is
changed to cause fluctuations in the optical coupling efficiency,
resulting in a failure in transmitting data in a stable manner.
[0026] In contrast, in the structure of the present invention, even
in the case where a deformation occurs in the second substrate,
since the amount of deformation is absorbed by the holding unit, it
is possible to prevent a deformation from occurring in the first
substrate on which the optical element is mounted. In this manner,
since the first substrate is made free from influences caused by
the second substrate, the positional relationship between the
optical element and the optical waveguide can be maintained
constant. Therefore, stable data transmission is executed without
fluctuations in the optical coupling efficiency.
[0027] In order to solve the above-mentioned problems, an optical
transmission module in accordance with the present invention is
provided with: an optical element that converts an electric signal
to an optical signal or converts an optical signal to an electric
signal; an optical transmission path that optically coupled with
the optical element to transmit an optical signal; a first
substrate that houses at least one end portion including an
incident/releasing port for an optical signal in the optical
transmission path and the optical element; and a second substrate
to which the optical transmission module is electrically connected,
and in this structure, the optical transmission module is further
provided with a holding unit having elasticity, which holds the
first substrate, and a connection member having a connection unit
that is connected to the second substrate.
[0028] In accordance with the above-mentioned structure, the first
substrate of the optical transmission module is connected to the
second substrate through the connection member. Since the first
substrate of the optical transmission module is held by the holding
unit having elasticity, it is allowed to move relative to the
second substrate. Consequently, even in the case where a
deformation such as a warp occurs in the second substrate due to
influences of, for example, an external force and heat, the amount
of deformation can be absorbed by the holding units so that no
deformation occurs in the first substrate.
[0029] In this manner, since the first substrate of the optical
transmission module is made free from influences caused by the
second substrate, the positional relationship between the optical
element and the optical waveguide can be maintained constant.
Therefore, stable data transmission is executed without
fluctuations in the optical coupling efficiency.
[0030] Moreover, in accordance with the above-mentioned structure,
since the optical transmission module is provided with the
above-mentioned connection member, the connecting process between
the optical transmission module and the second substrate can be
simplified. Furthermore, since the connection member can be
preliminarily attached to the first substrate, it is possible to
improve the attaching precision of the connection member to the
first substrate.
[0031] These and other objects, features and advantages of the
invention will be made clearer by a description given below. The
profit of the present invention will become apparent from the
ensuring explanation taken in conjunction with the attached
drawings.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0032] FIG. 1(a) is a side view that shows a connection state
between an optical transmission module and substrates in accordance
with the present embodiment.
[0033] FIG. 1(b) is a plan view that shows the connection state
between the optical transmission module and the substrates in
accordance with the present embodiment.
[0034] FIG. 2 is a side view that shows a schematic structure of
the optical transmission module.
[0035] FIG. 3 is a plan view that shows a schematic structure of
the optical transmission module.
[0036] FIG. 4(a) is a side view that shows a schematic structure of
the substrate.
[0037] FIG. 4(b) is a plan view that shows the schematic structure
of the substrate shown in FIG. 4(a).
[0038] FIG. 5(a) is a side view that shows a connection method
between the optical transmission module and the substrate.
[0039] FIG. 5(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 5(a).
[0040] FIG. 6(a) is a side view that shows another connection
method between the optical transmission module and the
substrate.
[0041] FIG. 6(b) is a plan view that shows another connection state
between the optical transmission module and the substrate shown in
FIG. 6(a).
[0042] FIG. 7(a) is a plan view that shows a connection state
between the optical transmission module and a substrate having a
step portion formed therein.
[0043] FIG. 7(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 7(a).
[0044] FIG. 8(a) is a side view that shows still another connection
method between the optical transmission module and the
substrate.
[0045] FIG. 8(b) is a plan view that shows still another connection
state between the optical transmission module and the substrate
shown in FIG. 8(a).
[0046] FIG. 9(a) is a side view that shows still another connection
method between the optical transmission module and the
substrate.
[0047] FIG. 9(b) is a plan view that shows still another connection
state between the optical transmission module and the substrate
shown in FIG. 9(a).
[0048] FIG. 10(a) is a side view that shows still another
connection method between the optical transmission module and the
substrate.
[0049] FIG. 10(b) is a plan view that shows still another
connection state between the optical transmission module and the
substrate shown in FIG. 10(a).
[0050] FIG. 11(a) is a side view that shows still another
connection method between the optical transmission module and the
substrate.
[0051] FIG. 11(b) is a plan view that shows still another
connection state between the optical transmission module and the
substrate shown in FIG. 11(a).
[0052] FIG. 12(a) is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where a protruding portion is formed on an elastic holding
unit.
[0053] FIG. 12(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 12(a).
[0054] FIG. 13(a) is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where a key-shaped elastic holding unit is installed.
[0055] FIG. 13(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 13(a).
[0056] FIG. 14(a) is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where a rectangular-pillar-shaped elastic holding unit is
installed.
[0057] FIG. 14(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 14(a).
[0058] FIG. 15(a) is a side view that shows still another
connection method between the optical transmission module and the
substrate.
[0059] FIG. 15(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 15(a).
[0060] FIG. 16(a) is a side view that shows still another
connection method between the optical transmission module and the
substrate.
[0061] FIG. 16(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 16(a).
[0062] FIG. 17(a) is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where a convex portion is formed on an outer wall of a package of
the optical transmission module.
[0063] FIG. 17(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 17(a).
[0064] FIG. 18(a) is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where a convex portion is formed virtually in the center of an
outer wall of a package of the optical transmission module.
[0065] FIG. 18(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 18(a).
[0066] FIG. 19 is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where an elastic member is placed between the outer wall of a
package of the optical transmission module and the convex portion,
shown in FIG. 17(a).
[0067] FIG. 20(a) is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where a holding unit is formed on an outer wall of a package of the
optical transmission module.
[0068] FIG. 20(b) is a side view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 20(a).
[0069] FIG. 21(a) is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where a holding unit is inserted between the optical transmission
module and a step portion formed on the substrate.
[0070] FIG. 21(b) is a side view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 21(a).
[0071] FIG. 22(a) is a side view that shows a connection method
between the optical transmission module and the substrate, in a
case where, after positioning the optical transmission module on
the substrate, an elastic holding unit is assembled thereon.
[0072] FIG. 22(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 22(a).
[0073] FIG. 23(a) is a side view that shows a connection method
between the optical transmission module and the substrate in a case
where a flat-plate-shaped elastic member is assembled on the
optical transmission module.
[0074] FIG. 23(b) is a plan view that shows a connection state
between the optical transmission module and the substrate shown in
FIG. 23(a).
[0075] FIG. 24 is a perspective view that shows a connection method
between the optical transmission module and the substrate in a case
where the optical transmission module is assembled on a box-shaped
elastic holding unit.
[0076] FIG. 25(a) is a side view that shows a state in which the
optical transmission module and the substrate are electrically
connected to each other by a wire.
[0077] FIG. 25(b) is a side view that shows a state in which the
optical transmission module and the substrate, as shown in FIG.
25(a), are electrically connected to each other by FPC.
[0078] FIG. 26 is a side view that shows a connection state between
the optical transmission module and the substrate in a case where
an adhesive sheet is used as an elastic holding unit.
[0079] FIG. 27(a) is a side view that shows a connection state
between the optical transmission module and the substrate by the
use of a securing pin.
[0080] FIG. 27(b) is a plan view that shows a connection state
between the optical transmission module and the substrate as shown
in FIG. 27(a).
[0081] FIG. 28 is a side view that shows a state in which
substrates are connected to one another by using FPC and an optical
waveguide.
[0082] FIG. 29(a) is a view that shows a detailed structure of the
optical transmission module shown in FIG. 28.
[0083] FIG. 29(b), which is an A-A' line cross-sectional view, is a
view that shows a connection method between the optical
transmission module and the substrate, in a case where a package is
inserted between elastic holding units.
[0084] FIG. 30 is a view that shows a state in which, in the
optical transmission module shown in FIG. 29(b), the gap between
the third substrate and the package is filled with a resin.
[0085] FIG. 31(a) is a perspective view that shows an external
appearance of a folding-type portable telephone provided with an
optical transmission module in accordance with the present
embodiment.
[0086] FIG. 31(b) is a block diagram that shows a portion of the
folding-type portable telephone, shown in FIG. 31(a), to which the
optical transmission module is applied.
[0087] FIG. 31(c) is a perspective plan view of a hinge portion in
the folding-type portable telephone shown in FIG. 31(a).
[0088] FIG. 32(a) is a perspective view that shows an external
appearance of a printing apparatus provided with an optical
transmission module in accordance with the present embodiment.
[0089] FIG. 32(b) is a block diagram that shows a main portion of
the printing apparatus shown in FIG. 32(a).
[0090] FIG. 32(c) is a perspective view that shows a curved state
of the optical transmission module when a printer head is moved
(driven) in the printing apparatus shown in FIG. 32(a).
[0091] FIG. 32(d) is a perspective view that shows a curved state
of the optical transmission module when a printer head is moved
(driven) in the printing apparatus shown in FIG. 32(a).
[0092] FIG. 33 is a perspective view that shows an external
appearance of a hard disk recording/reproducing apparatus provided
with an optical transmission module in accordance with the present
embodiment.
[0093] FIG. 34 is a side view that shows a connection state between
a conventional optical transmission module and a substrate.
[0094] FIG. 35 is a side view that shows a connection state between
a conventional optical transmission module and a substrate.
REFERENCE NUMERALS
[0095] 1 Optical transmission module [0096] 2 Substrate (second
substrate) [0097] 11 Optical waveguide (optical transmission path)
[0098] 12 Light-receiving/emitting element (optical element) [0099]
14 Package (first substrate) [0100] 21 Elastic holding unit
(connection member) [0101] 21a Pin (connection unit, electrode pin)
[0102] 21b Elastic portion (holding unit) [0103] 21c Electrode
BEST MODE FOR CARRYING OUT THE INVENTION
[0104] Referring to Figures, the following description will discuss
one embodiment of the present invention. FIG. 1(a) is a side view
that shows a connection state between an optical transmission
module 1 and a substrate 2 in accordance with the present
embodiment, and FIG. 1(b) is a plan view thereof.
[0105] First, referring to FIGS. 1(a) and 1(b), the following
description will explain a system for data communication in which
the optical transmission module 1 is utilized. Here, the optical
transmission module 1 is supposed to have a structure in which one
end of the optical transmission module 1 is mounted on a substrate
2A, with the other end of the optical transmission module 1 being
mounted on a substrate 2B, so as to execute data communication
inside an apparatus (not shown).
[0106] First, the optical transmission module 1 receives an
electric signal transmitted through the substrate 2A. Then, the
optical transmission module 1 converts the received electric signal
to an optical signal, and transmits the optical signal toward the
substrate 2B, and again converts it to an electric signal to be
transmitted to the substrate 2B.
[0107] By electrically connecting the optical transmission module 1
and the substrate 2 with each other, data communication between the
substrates in the apparatus is available. The following description
will discuss structures of the optical transmission module 1 and
the substrate 2 in detail. In the following description, by taking
into consideration an optical transmission module to be installed
in a small-size, thin apparatus, the optical transmission path is
explained as an optical waveguide; however, not limited to this,
the optical transmission path may be an optical fiber or the
like.
[0108] First, structures of the respective parts will be
explained.
(Structure of Optical Transmission Module)
[0109] As shown in FIG. 2, the optical transmission module 1 is
provided with an optical waveguide (optical transmission path) 11,
a light-receiving/emitting element (optical element) 12, a bonding
wire 13 and a package (first substrate) 14.
[0110] The optical waveguide 11 is configured by a core portion 11a
having a high refractive index and a clad portion 11b having a low
refractive index formed on the periphery of the core portion 11a so
as to be adjacent thereto, and transmits an optical signal that has
been made incident on the core portion 11a by utilizing total
reflection that is repeated on the border between the core portion
11a and the clad portion 11b. Since the core portion 11a and the
clad portion 11b are made from a polymer material having
flexibility, the optical waveguide 11 has flexibility.
[0111] Here, the following description will briefly discuss a
method for transmitting an optical signal in the optical waveguide
11.
[0112] As shown in FIG. 2, each of end faces of the optical
waveguide 11 is processed into a tilt face of 45 degrees so that an
optical signal, made incident on an incident/releasing port 11c of
the optical waveguide 11, is reflected by one of the end faces, and
its optical path is changed by 90 degrees so that it is directed
into the optical waveguide 11. The optical signal, directed into
the optical waveguide 11, is transmitted toward the other end face,
while repeating the total reflection therein. Thus, the optical
signal, reflected by the other end face, has its optical path
changed by 90 degrees, and is released outward from the
incident/releasing port 11c.
[0113] In the present embodiment, the angle of the end face of the
optical waveguide 11 is set to 45 degrees; however, not limited to
this, any structure may be used as long as it can direct an optical
signal into the optical waveguide 11. Another structure may be used
in which, for example, the end face of the optical waveguide 11 is
processed into a right angle, with an optical signal being made
incident and released on and from the end face in directions
orthogonal to the end face.
[0114] The light-releasing/emitting element 12 converts an electric
signal to an optical signal, or converts an optical signal to an
electric signal. Here, the light-receiving/emitting element 12 is
an element of a surface light-receiving/emitting type, and designed
to emit or receive an optical signal from a face on the side
opposite to a mounting face corresponding to a bottom plate of a
package 14, which will be described later, is mounted.
[0115] The bonding wire 13 is used for connecting the
light-receiving/emitting element 12 to an electric wire (not shown)
installed on the package 14, which will be described later, so as
to transmit an electric signal.
[0116] The package 14 is formed into a concave shape, with four
sides being surrounded by walls rising from the bottom plate, and
its upper opening is closed by a lid. End portions of the optical
waveguide 11, the light-receiving/emitting element 12 and the
bonding wire 13 are installed in the package 14. Moreover, the
package 14 is provided with an electrode (not shown) that is made
in contact with the electric wiring (not shown) and an external
device, and designed so that, when made in electrically contact
with the external device, for example, a substrate, an electric
signal is transmitted to the light-receiving/emitting element 12
through the bonding wire 13. Here, as the material used for the
package 14, selection may be made from various materials, such as
epoxy, ceramics, glass and plastic materials. Moreover, various
elements, such as a driving circuit used for driving the
light-receiving/emitting element 12, ICs, and driving circuits for
ICs, may be assembled in the package 14.
[0117] Here, the package 14 in the present embodiment has a
structure with a concave shape so as to house the end portions of
the optical waveguide 11, the light-receiving/emitting element 12
and the like, as described above; however, not limited to this
structure, for example, this may be formed as a flat-plate-shaped
substrate on which the end portions of the optical waveguide 11,
the light-receiving/emitting element 12 and the like are
mounted.
[0118] Next, referring to FIGS. 2 and 3, the following description
will discuss one example of a method for manufacturing the optical
transmission module 1 configured by the above-mentioned parts.
Here, in FIGS. 2 and 3, an axis that is in parallel with a
longitudinal direction of the optical waveguide 11 on the opening
face 14a of the package 14 is defined as a Y-axis, an axis that is
orthogonal to the Y-axis is defined as an X-axis, a coordinate
plane is defined as an X-Y plane, and an axis orthogonal to the X-Y
plane is defined as a Z-axis.
[0119] First, a light-receiving/emitting element 12, a bonding wire
13, an electric wire (not shown), an electric connection unit (not
shown) and an electrode (not shown) are preliminarily assembled
onto a package 14 secured by a jig or the like by using a method,
such as a soldering method. Next, while the optical waveguide 11 is
held by using an air chuck or the like, the
light-receiving/emitting element 12 and the optical waveguide 11
are position-adjusted by using an image recognition device (not
shown) placed above (Z-axis direction) the package 14. The optical
waveguide 11 is secured onto an opening face 14a of the package 14
by using a method such as bonding, at a position on the tilt end
face of the optical waveguide 11 where a projection portion
(incident/releasing port) 11c of the core portion and the
incident/releasing portion of the light-receiving/emitting element
12 are made coincident with each other.
[0120] In accordance with the optical transmission module 1
manufactured through the above-mentioned method, since the
peripheral portion of the incident/releasing port 11c of the
optical waveguide 11 can be supported, the distance between the
incident/releasing portion for an optical signal of the
light-receiving/emitting element 12 and the incident/releasing port
11c for an optical signal of the optical waveguide 11, as well as
the positional relationship between the two ports, can be
maintained constant. Therefore, by suppressing fluctuations in the
optical coupling efficiency between the light-receiving/emitting
element 12 and the optical waveguide 11, it is possible to provide
a stable transmission of data signal.
[0121] Here, the securing method for the optical waveguide 11 is
not particularly limited, and another structure may be used, as
long as the distance between the light-receiving/emitting element
12 and the incident/releasing port 11c for an optical signal of the
optical waveguide 11, as well as the positional relationship
between the two ports, can be maintained constant. For example,
another structure in which a supporting member for supporting the
end portion of the optical waveguide 11 is assembled in the package
14 may be used.
(Structure of Substrate)
[0122] FIG. 4(a) is a side view that shows a schematic structure of
a substrate (second substrate) 2, and FIG. 4(b) is a plan view
thereof. The substrate 2 is a general substrate to be connected to
an apparatus (not shown), and various elements are mounted thereon,
with electric signals being transmitted among the elements.
Moreover, an elastic holding unit (connecting member) 21, used for
holding the package 14 of the optical transmission module 1, is
formed on the substrate 2.
[0123] The elastic holding unit 21 is provided with a pin
(connecting portion, electrode pin) 21a to be inserted into a
through hole of the substrate 2, an elastic portion 21b for holding
the optical transmission module 1, and an electrode 21c that is
attached to the elastic portion 21b so as to be electrically
connected to the pin 21a. Here, the elastic portion 21b is made
from an elastic material capable of absorbing vibrations, impacts
and the like, and specific examples of the materials include
rubber, a spring, an adhesive sheet, a resin and the like.
Moreover, the electrode 21c is made in contact with an electrode
placed on the package 14 of the optical transmission module 1, and
electrically connected to the light-receiving/emitting element 12.
The elastic holding unit 21 is electrically connected and secured
to the substrate 2 by using solder, electrical connectors
(connecting portions) or the like.
[0124] Next, referring to FIGS. 1(a) and 1(b) as well as FIGS. 4(a)
and(b), the following description will discuss a method for
communication of electric signals on the optical transmission
module 1 and the substrate 2. The explanation is given by
exemplifying a structure in which a driving IC is mounted on a
substrate 2.
[0125] The driving IC mounted on one of the substrates 2A acquires
a command from a control unit (not shown), and releases an electric
signal. The electric signal thus released is transmitted through
the substrate 2A, and directed to the electrode 21c through the pin
21a of the elastic holding unit 21 so as to transmit data to the
other substrate 2B. The electric signal is then inputted to the
light-receiving/emitting element (light-emitting element) 12
through the package 14 that is made in contact with the electrode
21c. As described earlier, the electric signal, inputted to the
light-receiving/emitting element 12, is converted into an optical
signal, and transmitted through the optical waveguide 11. The
optical signal, transmitted through the optical waveguide 11, is
received by the light-receiving/emitting element (light-receiving
element) 12, and again converted to an electric signal. The
electric signal, thus converted, is directed to the electrode 21c
of the other elastic holding unit 21 that is made in contact with
the package 14 through the package 14, and inputted to, for
example, an amplifier or the like (not shown) that is mounted on
the other substrate 2B through the pin 21a so that it is amplified
to a desired output.
[0126] As described above, by electrically connecting the optical
transmission module 1 to the substrate 2 through the elastic
holding unit 21, it is possible to carry out data communication by
utilizing optical transmission.
[0127] The following description will discuss the structure of a
connecting portion of the optical transmission module 1 and the
substrate 2. In the following description, a coordinate plane in
parallel with a surface of the substrate 2 on which the elastic
holding unit 21 is mounted is defined as an X-Y plane, an axis that
is orthogonal to the X-Y plane is defined as a Z-axis, an axis in
parallel with the longitudinal direction of the optical waveguide
11 is defined as a Y-axis and an axis that is orthogonal to the
Y-axis is defined as an X-axis.
[0128] FIG. 5(a) is a side view that shows a connection method in
which the optical transmission module 1 is fitted to the substrate
2 from above (Z-axis direction) the substrate 2, and FIG. 5(b) is a
plan view that shows a connection state between the optical
transmission module 1 and the substrate 2.
[0129] As shown in FIGS. 5(a) and 5(b), a pair of the elastic
holding units 21 opposing to each other in a Y-axis direction are
formed on the substrate 2 by soldering or the like. Moreover,
electrodes 21c that are electrically connected to the package 14
are formed on the opposing faces of the paired elastic holding
units 21. Here, the electrode 21c may be attached to either one of
the paired elastic holding units 21. Moreover, the distance between
the paired elastic holding units 21 is preferably made shorter than
the length in the Y-axis direction of the package 14 of the optical
transmission module 1. That is, the distance is preferably adjusted
to such a degree as to allow the package 14, held between the
paired elastic holding units 21, to move toward the + side or -
side in the Y-axis direction.
[0130] In the above-mentioned structure, the optical transmission
module 1, inserted between the paired elastic holding units 21 from
the Z-axis direction as shown in FIG. 5(a), is subjected to
pressing forces in mutually different directions in the Y-axis
direction from the paired elastic holding units 21. With this
arrangement, the optical transmission module 1 can be held in an
electrically connected state with the substrate 2. Moreover, since
the optical transmission module 1 is connected to the substrate 2
through the elastic molding units 21, it is allowed to move
independently from the substrate 2 in its held state between the
paired elastic holding units 21.
[0131] For this reason, even in a case where a deformation or the
like occurs in the substrate 2, the influences thereof can be
absorbed by the elastic holding units 21, and are not given to the
optical transmission module 1. More specifically, for example, when
a warp occurs in the substrate 2 in a Z-axis direction (upward) due
to an external force and heat, the elastic holding units 21 are
deformed in mutually departing directions of the elastic holding
units 21 in the Y-axis direction. However, these deformations only
give influences to the pressing forces to be applied to the optical
transmission module 1 from the elastic holding units 21, and no
influences are given to the shape of the package 14 of the optical
transmission module 1. With this arrangement, even when a
deformation occurs in the substrate 2 on which the optical
transmission module 1 is assembled, the deformation of the optical
transmission module 1 can be prevented; thus, the distance between
the incident/releasing portion for an optical signal of the
light-receiving/emitting element 12 and the incident/releasing port
11c for an optical signal of the optical waveguide 11 of the
optical transmission module 1, as well as the positional
relationship between the two ports, can be maintained in a fixed
state. Therefore, it is possible to provide a stable data
transmission, without fluctuations in the optical coupling
efficiency.
[0132] In the present embodiment, since upon connecting the optical
transmission module 1 to the substrate 2, no heat such as soldering
is utilized, the assembling operation can be easily carried out.
Moreover, since the package 14 of the optical transmission module 1
are supported from the side faces (X-axis direction, Y-axis
direction), the connecting portion of the optical transmission
module 1 can be made smaller and thinner, in comparison with a
conventional structure using an electric connector.
[0133] Here, as shown in FIGS. 6(a) and 6(b), a pair of elastic
holding units 21 may be placed so as to face each other in the
X-axis direction. In this manner, the securing positions of the
elastic holding units 21 on the substrate 2 may be determined at
any positions as long as they allow the package 14 to be fitted
thereto, and can be adjusted on demand by taking into consideration
the layout relative to other elements to be assembled onto the
substrate 2.
[0134] Here, the above explanation has exemplified a structure in
which the paired elastic holding units 21 are placed, with the
package 14 of the optical transmission module 1 being supported
from the two sides; however, not limited by this structure, at
least one elastic holding unit 21 may be installed. In this case,
as shown in FIG. 7(a) and FIG. 7(b), a step portion 2a is formed at
a position facing the elastic holding unit 21 on the substrate 2,
and the package 14 may be fitted to the gap between the step
portion 2a and the elastic holding unit 21. The step portion 2a may
be integrally formed together with the substrate 2, or may be
secured thereto as a separated member. Here, the elastic holding
unit 21 is preferably formed into a curved shape toward the step
portion 2a side so as to easily insert the package 14 between the
two portions.
[0135] Moreover, as shown in FIGS. 8(a) and 8(b) to FIGS. 11(a) and
11(b), a plurality of the elastic holding units 21 may be placed on
the substrate 2 so as to provide three or more contact points
between the optical transmission module 1 and the elastic holding
units 21. With this arrangement, even when the optical transmission
module 1 is subjected to a stress exerted in the rotation direction
.theta. around the Z-axis on the substrate 2, the stress is
absorbed by the elastic holding units 21, and is not exerted onto
the optical transmission module 1. Therefore, the optical
transmission module 1 can be further stabilized.
[0136] Furthermore, as shown in FIGS. 12(a) and 12(b), another
structure may be proposed in which an elastic protrusion 21d having
a tilt face is attached to the upper portion of the elastic holding
unit 21 in the Z-axis direction. With this structure, the package
14 of the optical transmission module 1 can be easily inserted to a
gap between the elastic holding units 21, and the package 14 thus
inserted and held can be hardly detached from the substrate 2 even
when subjected to a stress in the Z-axis direction. Consequently,
the optical transmission module 1 can be held more stably. Here, in
order to hold the optical transmission module 1 more stably, a
concave portion 14b that receives the protrusion 21d may be formed
on the upper face of the package 14.
[0137] Here, although the present embodiment has a structure in
which the elastic holding unit 21 is attached to the side face of
the package 14 of the optical transmission module 1, for example,
another structure may be used in which the elastic holding unit 21
is placed between the substrate 2 and the package 14. That is, the
package 14 may be mounted on the upper face (Z-axis direction) of
the elastic holding unit 21 mounted on the substrate 2. With this
arrangement, even when a deformation occurs in the substrate 1 on
which the optical transmission module 1 is assembled, the
deformation of the optical transmission module 1 can be
prevented.
[0138] As shown in FIGS. 13(a) and 13(b), another structure may be
used in which elastic molding units 21, each having a key shape,
are placed at four portions on the substrate 2 that correspond to
the four corners of the package 14 of the optical transmission
module 1. With this arrangement, stresses in various directions,
occurring in the substrate 2, can be absorbed by the elastic
holding units 21 on the four corners, and are not exerted onto the
optical transmission module 1. For this reason, the optical
transmission module 1 can be further stabilized. In this manner,
since the four corners of the optical transmission module 1 are
held in the above-mentioned structure, stable data transmission is
available even when the respective elastic holding units 21 are
miniaturized. Therefore, the optical transmission module 1 can be
mounted on an apparatus having a smaller size.
[0139] Moreover, as shown in FIGS. 14(a) and 14(b), rectangular
pillar-shaped elastic holding units 21 may be placed at four
portions of the substrate 2, and cut-out portions (concave
portions) 14c in the Z-axis direction, which receive the elastic
holding units 21, may be formed at four corners of the package 14
of the optical transmission module 1. With this arrangement, the
same effects as those shown in FIGS. 13(a) and 13(b) can be
obtained. Moreover, the outside dimension of the package 14 which
houses the elastic holding units 21 is made virtually the same as
the outside dimension of the package 14 shown in FIGS. 13(a) and
13(b), it becomes possible to further miniaturize the entire
module.
[0140] Here, in the above-mentioned structures, the explanation has
been given by exemplifying a structure in which the package 14 of
the optical transmission module 1 is inserted into the gap between
the elastic holding units 21 from above in the Z-axis direction;
however, not limited by this structure, it may be inserted in the
Y-axis direction or in the X-axis direction. This structure is more
effective in a case where the optical transmission module 1 is
connected between laminated substrates or when no space is
available above the substrate 2 in the Z-axis direction. FIGS.
15(a) and 15(b) as well as FIGS. 16(a) and 16(b) show one example
of the above-mentioned structure, which is also applicable to a
structure provided with a plurality of elastic holding units
21.
[0141] Moreover, as shown in FIGS. 17(a) and 17(b), another
structure may be used in which a convex portion 14d is formed on
the outer wall of the package 14 of the optical transmission module
1, while a concave portion 21e that receives the convex portion 14d
is formed on the outer wall of the elastic holding unit 21. In
accordance with this structure, by inserting the convex portion 14d
of the package 14 into the concave portion 21e of the elastic
holding unit 21, the optical transmission module 1 can be held so
that the optical transmission module 1 can be easily inserted
between the elastic holding units 21 of the optical transmission
module 1, thereby making it possible to improve the efficiency of
the assembling operation. Here, in order to electrically connect
the optical transmission module 1 and the substrate 2 to each
other, the electrode 21c is preferably installed in the concave
portion 21e. Moreover, the attaching position of the convex portion
14d to the package 14 and the attaching position of the concave
portion 21e to the elastic holding unit 21 are not particularly
limited, and, for example, as shown in FIGS. 18(a) and 18(b), these
may be attached to virtually the middle position in the Z-axis
direction.
[0142] Moreover, as shown in FIG. 19, an elastic portion 14e, such
as a spring, may be formed between the outer wall of the package 14
and the convex portion 14d, shown in FIGS. 17(a) and 17(b).
[0143] Here, the present embodiment has exemplified a structure in
which, after the elastic holding unit 21 has been preliminarily
secured onto the substrate 2 by soldering or the like, the optical
transmission module 1 is assembled thereon; however, not limited to
this structure, for example, another structure may be used in which
the package 14 of the optical transmission module 1 is provided
with the elastic holding unit 21, and the elastic holding unit 21
is assembled onto the substrate 2. Moreover, as shown in FIGS.
20(a) and 20(b), holding units 21b are formed on the two side faces
(outer walls) of the package 14, and the package 14 may be inserted
into a pair of step portions 2a and 2b formed on the substrate 2 so
as to face each other. In the above-mentioned structure, in order
to easily insert the package 14 into the step portions 2a and 2d,
the holding unit 21b is preferably formed into a curved shape
outward from the package 14. With this structure, the package 14
can be held on the substrate 2, and, for example, even when the
substrate 2 is subjected to a stress exerted in the rotation
direction .theta. around the Z-axis, the stress is absorbed by the
elastic holding unit 21, and is not exerted onto the package 14 of
the optical transmission module 1. Therefore, it is possible to
carry out data transmission in a stable manner, without
fluctuations in the optical coupling efficiency. Moreover, since
this structure holds the side faces (X-axis direction, Y-axis
direction) of the package 14, the height in the Z-axis direction
can be suppressed, thereby making it possible to provide a thinner
device.
[0144] Moreover, as shown in FIGS. 21(a) and 21(b), another
structure may be used in which, on the inside of paired step
portions 2a and 2b formed on the substrate 2 so as to face each
other, a holding unit 21b is inserted between the package 14 and
the step portion 2a and/or the step portion 2b so as to hold the
side faces of the package 14 of the optical transmission module 1.
With this structure, since the deformation of the substrate 2 is
absorbed by the holding unit 21, the deformation of the package 14
can be prevented.
[0145] Furthermore, as shown in FIGS. 22(a) and 22(b), another
structure may be used in which, after the optical transmission
module 1 has been position at a desired position of the substrate
2, the elastic holding unit 21 is assembled on the substrate 2.
With this structure, since the mounting position of the optical
transmission module 1 can be freely determined, the assembling
efficiency on the substrate 2 can be improved. Here, as shown in
FIGS. 23(a) and 23(b), a structure may be adopted in which a
flat-plate-shaped elastic holding unit 21 is assembled in a manner
so as to cover the package 14 of the optical transmission module 1
from above (Z-axis direction). With this structure, the mounting
position of the optical transmission module 1 can be freely
determined, and even when a deformation occurs in the substrate 2
in the Z-axis direction, data transmission can be carried out more
stably.
[0146] Referring to FIG. 24, the following description will discuss
another structure of the elastic holding unit 21. FIG. 24 is a
perspective view that shows a method for connecting the optical
transmission module 1 and the substrate 2 to each other, upon
assembling the optical transmission module 1 on the elastic holding
unit 21.
[0147] As shown in FIG. 24, the elastic holding unit 21 is provided
with a box member 21f formed into a box shape with an upper face in
the Z-axis direction being open, pins 21a that are electrically
connected and secured onto the substrate 2 formed on the outer wall
face of the box member 21f, and elastic portions 21b, each made of
a spring or the like, which are attached to the inside of the box
member 21f so as to hold the package 14 of the optical transmission
module 1 at four positions. Moreover, at positions on the elastic
portions 21b to be made in contact with the package 14, electrodes
21c are formed. Here, the box member 21f is preferably molded and
formed by resin as an integral unit.
[0148] Moreover, as shown in FIG. 24, on the outer wall faces of
the package 14 of the optical transmission module 1, groove
portions (concave portions) 14f that receive the electrodes 21a are
preferably formed in the Z-axis direction.
[0149] In accordance with this structure, since the optical
transmission module 1 can be assembled by fitting the package 14
thereof to the elastic holding unit 21 having the box shape, the
efficiency of the attaching operation can be improved. Moreover,
since the optical transmission module 1 can be held by a plurality
of fulcrums, the optical transmission module 1 can be further
stabilized so that data transmission can be carried out in a stable
manner. Furthermore, since the elastic holding unit 21 can be
formed by using an integral resin molding operation, it becomes
possible to achieve superior general purpose operations, and
consequently to cut costs.
[0150] Here, the present embodiment has exemplified a structure in
which the electrodes 21c are formed on the elastic holding unit 21;
however, not limited to this structure, for example, as shown in
FIGS. 25(a) and 25(b), another structure may be used in which one
end of a wire 21g or a flexible printed circuit board (FPC) 21h is
connected to the substrate 2, with the other end being connected to
the package 14 of the optical transmission module 1. With this
structure, the substrate 2 and the optical transmission module 1
can be electrically connected to each other, without the elastic
holding unit 21 being interposed therebetween. In this case, as
shown in FIG. 26, by using an adhesive sheet 22 including no
electrodes as the elastic holding unit 21, the package 14 of the
optical transmission module 1 and the substrate 2 may be connected
to each other.
[0151] Furthermore, as a modified example of the elastic holding
unit 21 shown in FIGS. 25(a) and 25(b), the elastic holding unit 21
may be configured by an elastic portion 21b formed on the substrate
2 and a wire 21g or a flexible printed circuit board (FPC) 21h that
is electrically connected to the optical transmission module 1.
[0152] As shown in FIGS. 27(a) and 27(b), another structure may be
used in which a protrusion 14h having a through hole 14g is formed
on the outer wall of the package 14 of the optical transmission
module 1, and by using a securing pin 23 having a diameter smaller
than the inner diameter of the through hole 14g, the package 14 may
be connected to the substrate 2. With this structure, since a
clearance is formed between the securing pin 23 and the through
hole 14g, the package 14 is allowed to move relative to the
substrate 2. For this reason, the optical transmission module 1 is
made free from influences of a deformation occurring in the
substrate 2.
[0153] Here, the optical transmission module 1 of the present
embodiment may be installed together with electric wiring that
allows communication between the substrates 2, such as, for
example, an FPC 21h. In this case, as shown in FIG. 28, the length
of the optical waveguide 11 of the optical transmission module 1 is
preferably made longer than the length of the FPC 21h. With this
arrangement, even when a force is applied in the Y-axis direction,
no load is applied to the optical waveguide 11 so that it is
possible to prevent damages to the optical waveguide 11, and
consequently to carry out data communication in a stable
manner.
[0154] FIG. 29(a) is a view that shows a detailed structure of the
optical transmission module shown in FIG. 28, and FIG. 29(b), which
is an A-A' line cross-sectional view of FIG. 29(a), is a view that
shows a method for connecting the optical transmission module 1 and
the substrate 2, in a case where the package 14 is inserted between
the elastic holding units 21. As shown in FIGS. 29(a) and 29(b),
the optical transmission module 1 is configured by an optical
waveguide 11, a light-receiving/emitting element 12, a package 14,
an elastic holding unit 21 and a third substrate 24.
[0155] The package 14 is formed into a concave shape that is
provided with a substrate on which the light-receiving/emitting
element 12 is mounted and side walls that rise from the substrate
so as to house the optical waveguide 11 and the
light-receiving/emitting element 12 therein. The
light-receiving/emitting element 12 has a structure in which
electric terminals 24 of the light-receiving/emitting element 12
are secured onto the substrate by soldering. Moreover, the
substrate and the side walls are designed to be connected to each
other by a solder 25a. Here, an electric wire 26a that allows
electrical connection with the outside is installed in the side
walls.
[0156] The package 14 and the third substrate 24 are connected to
each other through the electric wire 26a placed in the side faces
of the package 14 by a solder 25b. In this manner, since the
package 14 and the third substrate 24 are connected only through
the flexible electric wiring 26a, stresses, exerted by those
actions, such as vibration, impact, thermal expansion, deflection,
tension, and fitting action, to be applied to the third substrate
24, are hardly transferred to the package 14. For this reason,
since the light-receiving/emitting element 12 and the optical
waveguide 11 become less susceptible to influences due to
deformation of the third substrate 24, it is possible to transmit
data in a stable manner, without causing fluctuations in the
optical coupling efficiency.
[0157] The elastic holding units 21 are formed on the substrate 2
so as to face each other, and provided with an electric wire 26b
having a spring structure that gives a pressing force (indicated by
a black arrow in FIG. 29(b)) in mutually facing directions. With
this structure, as shown in FIG. 29(b), the package 14 is inserted
between the opposing elastic holding units 21 (in a direction
indicated by a white arrow in the same Figure) so as to be secured
to the substrate 2. With this arrangement, it becomes possible to
maintain the package 14 with being electrically connected.
[0158] Here, the package 14 is preferably formed by a resin molding
operation, and allowed to have rigidity greater than that of the
third substrate 24. Moreover, the third substrate 24 is preferably
provided as a substrate having flexibility, such as an FPC.
[0159] FIG. 30 is a view that shows a state in which, in the
optical transmission module shown in FIG. 29(b), resin 27 is
injected between the third substrate 24 and the package 14.
[0160] The resin 27 to be injected preferably has an elastic
modulus that is smaller than the elastic modulus of the package 14.
With this structure, since stresses, exerted by those actions, such
as vibration, impact, thermal expansion, warping, tension, and
fitting action, to be applied to the third substrate 24, are
absorbed by the resin 27, those stresses are hardly transmitted to
the package 14. For this reason, since the light-receiving/emitting
element 12 and the optical waveguide 11 become less susceptible to
influences due to deformation of the third substrate 24, it is
possible to transmit data in a stable manner, without causing
fluctuations in the optical coupling efficiency.
[0161] Moreover, the resin 27 is preferably made to have a hardness
that is higher than the hardness of the package 14. Since this
structure makes the stress occurring in the third substrate 24
interrupted by the resin 27, the stress is hardly transferred to
the package 14. Thus, it becomes possible to obtain the same
effects as those described above.
(Application Examples)
[0162] Lastly, for example, the optical transmission module 1 of
the present embodiment may be applied to the following electronic
apparatuses.
[0163] First, the first application example includes hinge portions
of an electronic apparatus of a folding type, such as a
folding-type portable telephone, a folding-type PHS (Personal
Handyphone System), a folding-type PDA (Personal Digital Assistant)
and a folding-type notebook personal computer.
[0164] FIGS. 31(a) to 31(c) show examples in which the optical
transmission module 1 is applied to a folding-type portable
telephone 40. That is, FIG. 31(a) is a perspective view that shows
the outer appearance of the folding-type portable telephone 40
having a built-in optical transmission module 1.
[0165] FIG. 31(b) is a block diagram that shows a portion in which
the optical transmission module 1 is applied in the folding-type
portable telephone 40 as shown in FIG. 31(a). As shown in this
Figure, a control unit 41 formed on the main body 40a side of the
folding-type portable telephone 40, an external memory 42 formed on
the side of a lid (driving unit) 40b that is installed on one end
of the main body so as to be rotatable with its hinge portion
serving as an axis, a camera unit (digital camera) 43 and a display
unit (liquid crystal display) 44 are respectively connected to one
another by the optical transmission module 1.
[0166] FIG. 31(c) is a perspective plan view that shows the hinge
portion (portion surrounded by a broken line) in FIG. 31(a). As
shown in this Figure, the optical transmission module 1 is wound
around a supporting rod in the hinge portion, and allowed to bend
so that the control unit formed on the main body side, the external
memory 42, the camera unit 43 and the display unit 44, placed on
the lid side, are respectively connected to one another.
[0167] By applying the optical transmission module 1 to such a
folding-type electronic apparatus, it becomes possible to achieve
high-speed communication with a large capacity within a limited
space. Therefore, it is suitably applied to an apparatus that
requires high-speed data communication with a large capacity, and
also has to achieve a small size, for example, such as a
folding-type liquid crystal display.
[0168] The second application example of the optical transmission
module 1 includes apparatuses having a driving unit, such as a
printer head in a printing apparatus (electronic apparatus) and a
reading unit in a hard disk recording/reproducing apparatus.
[0169] FIGS. 32(a) to 32(c) show examples in which the optical
transmission module 1 is applied to a printing apparatus 50. FIG.
32(a) is a perspective view that shows the outer appearance of the
printing apparatus 50. As shown in this Figure, the printing
apparatus 50 is provided with a printer head 51 that carries out a
printing process on paper 52, while being moved in a width
direction of the paper 52, and one end of the optical transmission
module 1 is connected to this printer head 51.
[0170] FIG. 32(b) is a block diagram that shows a portion in which
the optical transmission module 1 is applied to the printing
apparatus 50. As shown in this Figure, one end of the optical
transmission module 1 is connected to the printer head 51, and the
other end is connected to the substrate on the main body side in
the printing apparatus 50. Here, a control means and the like, used
for controlling the operations of the respective units of the
printing apparatus 50, are installed in the substrate on the main
body side.
[0171] FIGS. 32(c) and 32(d) are perspective views that show a
curved state of the optical waveguide 11 of the optical
transmission module 1, in a case where the printer head 51 is
shifted (driven) in the printing apparatus 50. As shown in this
Figure, when the optical transmission module 1 is applied to a
driving unit such as the printer head 51, the curved state of the
optical waveguide 11 is changed by the driving operations of the
printer head 51, with the respective positions of the optical
waveguide 11 being curved repeatedly.
[0172] Therefore, the optical transmission module 1 in accordance
with the present embodiment is desirably applied to these driving
units. Moreover, by applying the optical transmission module 1 to
these driving units, it becomes possible to achieve high-speed
communication with a large capacity by using the driving units.
[0173] FIG. 33 shows an example in which the optical transmission
module 1 is applied to a hard disk recording/reproducing apparatus
60.
[0174] As shown in this Figure, the hard disk recording/reproducing
apparatus 60 is provided with a disk (hard disk) 61, a head
(reading/writing head) 62, a substrate introducing unit 63, a
driving unit (driving motor) 64 and the optical transmission module
1.
[0175] The driving unit 64 drives the head 62 in a radial direction
of the disk 61. The head 62 reads information recorded on the disk
61, and also writes information on the disk 61. Here, the head 62,
which is connected to the substrate introducing unit 63 through the
optical transmission module 1, allows the information read from the
disk 61 to be propagated to substrate introducing unit 63 as an
optical signal, and receives an optical signal of information,
transferred from the substrate introducing unit 63, to be written
onto the disk 61.
[0176] In this manner, by applying the optical transmission module
1 to a driving unit such as the head 62 of the hard disk
recording/reproducing apparatus 60, it becomes possible to achieve
high-speed communication with a large capacity.
[0177] The present invention is not intended to be limited by the
above-mentioned embodiments, and various modifications may be made
therein within the scope of the claims. That is, embodiments,
obtained by combining technical means modified on demand within the
scope of the claims, are also included within the technical scope
of the present invention.
[0178] As described above, in the connection member of the present
invention that relates to the connection member described above,
the holding unit is preferably installed on the second
substrate.
[0179] In accordance with the above-mentioned structure, since the
holding unit is installed on the second substrate, the first
substrate, held on the second substrate, is allowed to move
relative to the second substrate. For this reason, even in a case
where a deformation, such as a warp or the like, occurs in the
second substrate due to influences of, for example, an external
force and heat, since the amount of the deformation can be absorbed
by the holding unit, no deformation occurs in the first
substrate.
[0180] Moreover, in the connection member of the present invention
that relates to the connection member described above, the holding
unit is preferably allowed to hold a face of the first substrate in
a direction that intersects with a face opposing to the second
substrate face to which the connection unit is connected.
[0181] In accordance with the above-mentioned arrangement, the
first substrate has its face, extending in a direction orthogonal
to the face opposing to the second substrate face to which the
connection unit is connected of the first substrate, held by the
holding unit. That is, since the connection member is not connected
between the second substrate and the first substrate, or to a face
of the first substrate on the side opposite to the face opposing to
the second substrate, but connected to a side face of the first
substrate, with the result that the height in a direction
orthogonal to the second substrate face can be suppressed, thereby
making it possible to make the entire module including the second
substrate and the first substrate smaller and thinner.
[0182] Moreover, the connection member of the present invention,
which relates to the above-mentioned connection member, is provided
with at least one pair of the holding units, and the paired holding
units are preferably allowed to hold the first substrate by
applying pressing forces in opposite directions to the first
substrate.
[0183] In accordance with the above-mentioned arrangement, the
first substrate is held by receiving pressing forces in opposing
directions from at least the pair of holding units.
[0184] With this arrangement, the first substrate is held by
elastic holding units, with the side faces of the first substrate
being sandwiched thereby; therefore, even in the case where a
deformation such as a warp occurs in the second substrate due to
influences of, for example, an external force and heat, the amount
of deformation can be absorbed by the holding units so that no
deformation occurs in the first substrate. Therefore, the
positional relationship between the optical element to be mounted
on the first substrate and the optical waveguide can be maintained
constant so that data transmission can be carried out in a stable
manner without fluctuations in the optical coupling efficiency.
Moreover, since the side faces of the first substrate are held, the
entire module including the second substrate and the first
substrate can be made smaller and thinner.
[0185] Moreover, in the connection member of the present invention
that relates to the connection member described above, the
connection unit is preferably formed into a concave shape so as to
receive the first substrate, while the holding unit is preferably
formed on a face inside the concave portion, which opposes to the
inner space.
[0186] In accordance with the above-mentioned arrangement, since
the first substrate is held by the elastic holding units inside the
concave portion of the connection unit, with the side faces of the
first substrate being sandwiched thereby, the first substrate can
be held more stably, and data transmission can be carried out more
stably. Moreover, since the side faces of the first substrate can
be held, the entire module including the second substrate and the
first substrate can be made smaller and thinner.
[0187] Moreover, in the connection member of the present invention
that relates to the connection member described above, the holding
unit is preferably provided with an electrode at the connection
position to the first substrate.
[0188] In accordance with the above-mentioned arrangement, since
the holding unit is provided with the electrode at the connection
position to the first substrate, the first substrate is maintained
in the connected state to the electrode, even when the first
substrate is moved relative to the second substrate. Therefore, it
is possible to carry out data transmission in a stable manner.
[0189] Moreover, since the holding unit is provided with the
electrode, it is not necessary to install a member used for
electrically connecting the first substrate and the second
substrate to each other in a separate manner so that the space on
the second substrate can be effectively utilized, and the entire
module including the second substrate and the first substrate can
be made smaller.
[0190] In the connection member of the present invention that
relates to the above-mentioned connection member, the connection
unit is preferably provided with an electrode pin that is
electrically connected to the second substrate.
[0191] In accordance with the above-mentioned arrangement, since
the connection unit is provided with the electrode pin that is
electrically connected to the second substrate, it can be connected
to the second substrate by utilizing soldering. Moreover, the
second substrate and the first substrate can be electrically
connected to each other through the electrode pin.
[0192] In the optical transmission module of the present invention
that relates to the above-mentioned optical transmission module,
the holding unit is preferably formed on the first substrate.
[0193] With this arrangement, since, upon connecting the first
substrate and the second substrate to each other, an elastic
holding unit is interposed between the first substrate and the
second substrate so that the first substrate is allowed to move
relative to the second substrate. With this arrangement, even in
the case where a deformation such as a warp occurs in the second
substrate due to influences of, for example, an external force and
heat, since the amount of deformation can be absorbed by the
holding unit, no deformation occurs in the first substrate.
[0194] Moreover, in the optical transmission module of the present
invention that relates to the above-mentioned optical transmission
module, the first substrate is preferably provided with a concave
portion that receives the connection member.
[0195] In accordance with the above-mentioned arrangement, since
the first substrate is provided with the concave portion that
receives the connection member, the outside dimension of the first
substrate that has received the connection member can be made
smaller in comparison with the first substrate having no concave
portion. Therefore, the entire module including the second
substrate and the optical transmission module can be
miniaturized.
[0196] Moreover, in the optical transmission module of the present
invention that relates to the above-mentioned optical transmission
module, the first substrate is formed into a concave shape
constituted by a bottom plate on which the optical element is
mounted and side walls that rise from the bottom plate in a manner
so as to surround the periphery of the optical element, and the
concave portion that receives the connection member is preferably
formed on a face on the side walls on the side opposite to the face
that faces the inner space of the concave shape.
[0197] In accordance with the above-mentioned structure, the
concave portion that receives the connection member is formed on a
face on the side walls that rise from the bottom plate holding the
optical element in a manner so as to surround the periphery of the
optical element, on the side opposite to the face that faces the
inner space of the concave shape.
[0198] With this arrangement, the outside dimension of the first
substrate that receives the connection member can be made smaller
in comparison with the first substrate having no concave portion.
Therefore, the entire module including the second substrate and the
optical transmission module can be miniaturized.
[0199] Moreover, in the optical transmission module of the present
invention that relates to the above-mentioned optical transmission
module, the connection member is preferably provided with an
electrode to be electrically connected to the second substrate.
[0200] In accordance with the above-mentioned arrangement, the
connection member is provided with the electrode to be electrically
connected to the second electrode. Therefore, the optical
transmission module can be electrically connected to the second
substrate by connecting the connection member to the second
substrate. Since it is not necessary to provide a member used for
electrically connecting the optical transmission module to the
second substrate in a separate manner, the space on the second
substrate can be effectively utilized, and the entire module
including the second substrate and the optical transmission module
can be miniaturized.
[0201] In the optical transmission module of the present invention
that relates to the above-mentioned optical transmission module,
the first substrate preferably has bending rigidity that is higher
than that of the second substrate.
[0202] In accordance with the above-mentioned arrangement, the
first substrate has bending rigidity that is higher than that of
the second substrate; therefore, even in the case where a
deformation such as warping occurs in the second substrate due to
influences of an external force, the first substrate becomes less
susceptible to occurrence of a deformation. Therefore, the
positional relationship between the optical element to be mounted
on the first substrate and the optical waveguide can be maintained
constant so that data transmission can be carried out in a stable
manner without fluctuations in the optical coupling efficiency.
[0203] Specific embodiments or examples, given in the detailed
description of the present invention, are only used for clarifying
the technical contents of the present invention, and are not
narrowly interpreted in a limited manner to such specific examples,
and various modifications may be made therein within the spirit of
the present invention and the scope of the following claims.
INDUSTRIAL APPLICABILITY
[0204] Since stable data transmission is available by using an
flexible optical cable, the module of the present invention is
utilized for data transmission among substrates in many fields,
such as portable telephones, notebook PCs, PDAs (portable
information terminals), liquid crystal TVs, desktop monitors,
printers, electric appliances for automobiles, servers, routers,
testers, and other consumer appliances and general-use
apparatuses.
* * * * *